Sheep Pocket Guide (continued)

AS-989, May 1996

Breeding

Breeds
Ram Selection
Gestation Table
Lambing Records

Breeds of Sheep

							
		   Ave Mature Wt			        Grease
		  ---------------  Growth              Milking  Fleece
 		   Rams	 Ewes       Rate  Prolificacy  Ability  Weight
----------------------------------------------------------------------
EWE BREEDS:
Border Leicester  175-250  140-180  M-H      M-H        M-H      8-12
Corriedale	  175-275  130-180   M        M          M	10-17
Finnsheep         175-225  120-160  L-M      H++         H       4-8
Merino	          150-225  110-150  L-M      L-M         M       8-14
Polypay	          200-250  140-180   M        H          H       7-12
Rambouillet	  250-300  150-200  M-H      L-M         M       8-18
Targhee	          200-300  150-200  M-H       M          M      10-14

DUAL PURPOSE BREEDS:
Columbia	  225-350  150-225   H        M          M      10-16
Dorset		  200-250  140-180  M-H      M-H         H       5-9
Lincoln		  250-350  200-250   M        M         L-M     12-20
Montadale         200-275  150-200   M        M          M       8-12
Romney            200-275  150-200   M        M         L-M      8-12

RAM BREEDS:	
Cheviot	          160-200  120-150   M        M          M       5-10
Hampshire	  250-325  175-225   H       M-H         H       6-10
Oxford	          200-300  150-200  M-H       M          M       8-12
Shropshire	  200-250  150-180  M-H       M          M       6-10
Southdown	  175-225  130-180   M        M          M       5-8
Suffolk	          250-350  180-250   H+       H          H       5-8
----------------------------------------------------------------------

Ram Selection

Rams should be selected that have the genes for rapid gains, desirable carcass qualities, and the ability to sire daughters with greater reproductive ability. The key factor in a profitable sheep enterprise is total pounds of lamb produced per ewe per year.

The level of fertility in a ram is important to the overall sheep program. A highly fertile ram will not only settle a greater number of ewes earlier in the breeding season but will also fertilize a higher proportion of twin eggs than rams with poor fertility. In addition, data suggest that highly fertile rams tend to sire daughters that reach sexual maturity at an earlier age and ovulate more ova during each heat period.

Studies have indicated that as testicular size increases there is also an increase in sperm numbers, improving overall semen quality. Research indicates that rams with larger testicles are capable of superior reproductive performance and will produce offspring with greater reproductive capacity.

Sexual maturity of ram lambs is related to both age, weight, and genetics. These factors are influenced by heredity and environmental factors such as climate and nutrition. Sexual maturity of the ram lamb appears to be more closely related to body weight than age. Studies indicate sexual maturity in rams occurs at a body weight nearing 40 to 60 percent of the mature weight for that breed. Investigations indicate that full development of a ram's reproductive organs occur somewhere between 100 to 130 days of age. Most lambs are first ready to reproduce by 150 days. Sexual maturity may be delayed beyond one year of age if the ram lamb is subjected to inadequate nutrition and/or unfavorable environmental conditions.

Breeding has no adverse effect on the growing ram lamb as long as adequate nutrition is supplied. However, this does not mean that all ram lambs will satisfactorily breed ewes. Ram lambs may be ready, willing and even able to reproduce by five months of age or earlier, but their ability to settle a large number of ewes still needs time to develop. Researchers studying semen production in ram lambs have noted that sperm motility scores dramatically improve from six to nine months of age.

Physically, a ram should be examined from head to toe. He should have normal eyes with no indication of inverted eyelids, and a mouth with a normal bite. He should be tipped over and his testicles checked for uniformity and size. No evidence of epididymitis or pizzle rot should be present. Be skeptical about any abnormality affecting any portion of the reproductive tract. His feet should be free of defects or diseases. His fleece should be free of black fibers.

Check the ram closely for external parasites. Healthy sheep have a characteristic pink color to their skin (slightly darker in the black-face breeds). Note the color of the mucous membrane of the mouth and eyes. Absence of color indicates anemia, yellowness may indicate a liver disorder. When in doubt about a health question, seek the advice of a veterinarian.

Gestation Table

Breeding Date in Upper Line; Lambing Date in Lower Line

Lambing Records

----------------------------------------------------------------------
	
Lamb   Ewe    Sire   Birth         Birth  Wean   Wean
ID     ID     ID     Date   Sex    WT     WT     Date   Remarks
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AS-989, May 1996